Method for modifying polystyrene after polymerization by phosphorylation of aromatic C-H bond under catalysis of manganese

Abstract

The invention discloses a method for modifying polystyrene after polymerization by phosphorylation of an aromatic C (sp2)-H bond under the catalysis of manganese, and relates to the technical field of functional modification of high polymer materials. According to the preparation method, polystyrene is directly subjected to chemical modification, phosphate and polystyrene are taken as raw materials, manganese is taken as a catalyst, phosphorylation of polystyrene is realized under mild experimental conditions, and functional polystyrene containing phosphate groups is obtained. The structure of the phosphorylated polystyrene polymer is shown as a formula (I), and R is one of methyl, ethyl, butyl, 2, 2, 2-trifluoroethyl or phenyl. The method has the advantages of mild reaction conditions, simple post-treatment and the like, a phosphate group can be directly introduced to a polystyrene main chain, and a new strategy is provided for polystyrene modification and waste polystyrene recovery. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the technical field of functional modification of polymer materials, and in particular to a manganese-catalyzed aromatic C (sp 2 A method for post-polymerization modification of polystyrene by phosphorylation of )-H bonds. Background Art

[0002] Polystyrene is widely used in daily life and production due to its excellent thermal stability, chemical resistance and physical properties. With the rapid growth of its demand, the recycling problem has become increasingly prominent, and the recycling and modification of polystyrene materials are particularly important. Among them, phosphorus-containing polystyrene polymers are widely used in flame retardants, fuel cells, adhesives and environmentally recycled metal complexes due to their excellent properties.

[0003] At present, the phosphorylation of polystyrene is mainly carried out by physical blending or free radical polymerization before polymerization. This has the effect on the thermal stability and mechanical properties of the polystyrene body, or the problem of uneven monomer reaction, which leads to anisotropic properties of the composite material. Therefore, it is necessary to find a new way to achieve the phosphorylation of polystyrene. The post-polymerization modification strategy of the polymer just fits this idea. However, since polystyrene is composed of CC bonds and CH bonds, its direct functionalization is still a relatively large challenge.

[0004] The present invention provides a manganese-catalyzed aromatic C (sp 2 A method for post-polymerization modification of polystyrene by phosphorylation of )-H bonds. Inexpensive and less toxic manganese compounds are used as catalysts to directly phosphorylate the CH bonds of polystyrene. This method also has the advantages of mild reaction conditions and simple reaction steps. It provides a new strategy for polystyrene modification and waste polystyrene recycling. Summary of the invention

[0005] The object of the present invention is to provide a manganese-catalyzed aromatic C (sp 2 A method for post-polymerization modification of polystyrene by phosphorylation of )-H bonds. The method uses a low-cost and less toxic manganese compound as a catalyst to achieve a direct phosphorylation reaction of the CH bonds of polystyrene with mild reaction conditions and simple post-treatment.

[0006] To achieve the purpose of the present invention, the following technical scheme is adopted.

[0007] A manganese-catalyzed aromatic C(sp 2 The invention discloses a method for modifying polystyrene after polymerization by phosphorylation of )-H bonds, comprising the following steps: adding polystyrene, phosphate ester and manganese catalyst into an organic solvent for heating reaction, and after the reaction, post-treating to obtain a phosphorylated polystyrene polymer.

[0008] The reaction formula is as follows:

[0009]

[0010] Wherein, R is a C1-C4 alkyl group, a trifluoroethyl group, a substituted or unsubstituted phenyl group, and the substituent on the phenyl group is a C1-C4 alkyl group or a C1-C4 alkoxy group;

[0011] y=1-x, y represents the grafting rate.

[0012] The range of y is 5% to 20%, and further selected from 8 to 14%.

[0013] In the present invention, a specific catalyst is used to make polystyrene (PS, M n =151.0kg·mol -1 , D = 1.97) and the CH bond phosphorylation reaction of phosphate ester occurs, the reaction conditions are mild and the post-treatment is simple.

[0014] Preferably, the polystyrene can be any one of commercial high molecular weight polystyrene and waste foam polystyrene.

[0015] Preferably, R is methyl, ethyl, butyl, 2,2,2-trifluoroethyl or phenyl.

[0016] Preferably, in terms of molar amount, the ratio of polystyrene: phosphate ester: manganese catalyst is 1:1-1.1:0.2-0.5; further preferably, the ratio of polystyrene: phosphate ester: manganese catalyst is 1:1:0.2.

[0017] In the present invention, the catalyst used is anhydrous manganese acetate, which is relatively cheap and less toxic than other metal catalysts used in polymers, and can effectively achieve the phosphorylation of polystyrene.

[0018] Preferably, the reaction temperature is 70-90°C and the reaction time is 8-15 hours. More preferably, the reaction temperature is 80°C and the reaction time is 12 hours. Too high a reaction temperature will result in a poor phosphorylation degree, while too low a reaction temperature will be unfavorable for the reaction to occur. Too long a reaction time will increase the reaction cost, while too short a time will not guarantee the occurrence of the reaction.

[0019] In the present invention, most organic solvents can make the reaction occur, but the grafting rate varies greatly or may cause polymer chain rupture. As a preferred solvent, DMF is used, and the reactant is more successfully converted into the target product. Generally speaking, the amount of organic solvent used for 0.5 mmol of polystyrene is about 1.0 mL.

[0020] Preferably, the phosphorylated polystyrene polymer is one of the compounds represented by formula (I-1) to formula (I-5):

[0021]

[0022]

[0023] The post-processing steps in the present application are: dissolving and eluting the reaction solution with dichloromethane and transferring it to a pear-shaped separatory funnel, washing the organic phase with water three to five times, drying with anhydrous sodium sulfate, concentrating and precipitating it into methanol, filtering to obtain a solid precipitate, and vacuum drying.

[0024] In the above preparation method, the polystyrene, phosphate, anhydrous manganese acetate and N,N-dimethylformamide are generally commercially available products and are easily obtained from the market.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. Directly introduce phosphate into the main chain structure of polystyrene;

[0027] 2. The catalyst used is a manganese complex with low price and low toxicity;

[0028] 3. Compared with other methods of phosphorylating polystyrene, this modification method has better compatibility with the polymer; the preparation method has mild reaction conditions and simple post-processing. Description of the drawings:

[0029] In order to better illustrate the present invention, the drawings required for use in the embodiments or prior art descriptions are briefly introduced below.

[0030] Figure 1 The hydrogen spectrum, phosphorus spectrum and infrared spectrum of the compound obtained in Example 1;

[0031] Figure 2 The hydrogen spectrum, phosphorus spectrum and infrared spectrum of the compound obtained in Example 2;

[0032] Figure 3 The hydrogen spectrum, phosphorus spectrum and infrared spectrum of the compound obtained in Example 3;

[0033] Figure 4 The hydrogen spectrum, phosphorus spectrum and infrared spectrum of the compound obtained in Example 4;

[0034] Figure 5 The hydrogen spectrum, phosphorus spectrum and infrared spectrum of the compound obtained in Example 5;

[0035] Figure 6 The hydrogen spectrum, phosphorus spectrum and infrared spectrum of the compound obtained in Example 6;

[0036] Figure 7 It is the GPC curve diagram of Example 1-6 and PS;

[0037] Figure 8 TGA and DTG diagrams of Examples 1-5 and PS. Specific implementation methods

[0039] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below. The features and performances of the present application are further described in detail below in conjunction with the embodiments, which are all the best embodiments of the present application.

[0040] The obtained polymer was measured by nuclear magnetic resonance (NMR), infrared (FT-IR), gel permeation chromatography (GPC), thermogravimetric analyzer (TGA) and micro combustion calorimeter (MCC). 1 H NMR and 31 P NMR was measured in a nuclear magnetic resonance instrument (400UItraShield), the sample was dissolved in deuterated chloroform (CDCl3), and scanned 8 times, 500 times, and 50 times at 25°C; IR was measured in an infrared spectrometer (Nicolet iS20), the sample was scanned 8 times, and the resolution was 4cm -1 , wavelength test range is 500-4000cm -1 ; The number average molecular weight (M) of the target product was tested in a (Waters Model 1525 HPLC pump). n ), weight average molecular weight (M w ) and polydispersity coefficient (D,M w / M n ): the mobile phase was THF, the flow rate was 1.0 mL / min, and the retention time was 40 min; TGA and DTG were measured in a thermogravimetric analyzer (TGA Q50), specifically: 3-10 mg of the sample was heated from 40-600 °C at 10 °C / min under a nitrogen atmosphere; MCC was measured in a micro combustion calorimeter (MODEL-MCC-3) to test the heat release capacity (HRC, J / g·K), specific heat release rate (pHRR, W / g), combustion heat (THR, kJ / g) and temperature at peak heat release rate (T pHRR , ℃), predict the fire resistance of the material. Compared with the raw material, the decrease of HRC, pHRR and THR indicates the enhancement of flame retardancy.

[0041] Examples 1-6

[0042] According to the raw material ratio in Table 1, polystyrene (0.5 mmol), phosphate (0.5 mmol), anhydrous manganese acetate (0.1 mmol) and 1.0 mL of organic solvent were added to a 25 mL Schlenk tube, and the mixture was stirred evenly. After the reaction was completed according to the reaction conditions in Table 2, the reaction solution was dissolved and washed with dichloromethane and transferred to a pear-shaped separatory funnel. The organic phase was washed with water three to five times, dried with anhydrous sodium sulfate, and concentrated. The mixed solution was poured into methanol to precipitate the product, and then filtered to obtain a solid precipitate, which was vacuum dried to obtain the corresponding phosphorylated polystyrene polymer. The reaction process is as follows:

[0043]

[0044] Table 1 Raw material ratio of Examples 1-6

[0045]

[0046]

[0047] Table 2 Reaction conditions and reaction results of Examples 1-6

[0048]

[0049] T is the reaction temperature, t is the reaction time, commercial polystyrene (PS, M n =151.0kg·mol -1 , The grafting rate is the mol% of the phosphate groups attached to PS after the phosphorylation reaction. The integral of the -CH- signal peak on the polystyrene main chain is set to 1, and the other signal peaks are integrated. The integral of the characteristic peak on the phosphorylated polymer divided by the number of protons it contains is the grafting rate of the polymer.

[0050] Table 3 TGA data of Examples 1-5 and PS

[0051]

[0052] T d,5％ , T d,50％ and T d,max They represent the temperatures at which the mass loss is 5%, 50% and the fastest respectively; the carbon residue rate is the solid carbon residue rate at 600°C; nd means it cannot be determined.

[0053] Table 4 MCC data of PS and examples

[0054]

[0055] Structural confirmation data of the compounds prepared in Examples 1-6:

[0056]

[0057] Embodiment 1:

[0058] 1 H NMR(CDCl3,400MHz): δ7.8-6.78(br,3H,C6 H 5),6.78-5.95(br,2H,C6 H 5),4.07-3.29(br,2H,OC H 3),2.28-1.69(br,1H C H CH2), 1.69-1.18(br, 2H CHC H 2).

[0059] 31 P NMR (CDCl3, 162 MHZ): δ 20.31.

[0060] IR(neat,ATR,cm -1 ):3103,3083,3059,3026,3000,2922,2850,1601,1582,1493,1451,1375,1259,1183,1154,1127,1050,1028,907,823,800,755,697,539.

[0061]

[0062] Embodiment 2:

[0063] 1 H NMR(CDCl3,400MHz):δ7.18-6.76(br,3H,C6 H 5),6.76-5.98(br,2H,C6 H 5),4.3-3.5(br,2H,OC H 2CH3),2.25-1.60(br,1H C H CH2),1.60-1.05(br).

[0064] 31 P NMR (CDCl3, 162 MHZ): δ 17.37.

[0065] IR(neat,ATR,cm -1):3082,3060,3026,3000,2979,2923,2850,1682,1602,1583,1493,1452,1390,1367,1251,1181,1162,1155,1129,1096,1052,1022,962,907,831,811,790,757,750,696,620,561,539.

[0066]

[0067] Embodiment 3:

[0068] 1 H NMR(CDCl3,400MHz): δ7.16-6.78(br,3H,C6 H 5),6.78-6.22(br,2H,C6 H 5),4.30-3.54(br,2H,OC H 2CH2CH2CH3),2.16-1.67(br,1H C H CH2),1.67-0.96(br),0.96-0.72(br).

[0069] 31 P NMR (CDCl3, 162 MHZ): δ 17.11.

[0070] IR(neat,ATR,cm -1 ):3103,3082,3059,3026,3001,2957,2924,2870,2851,1601,1583,1542,1492,1452,1409,1377,1328,1312,1256,1233,1182,1154,1128,1065,1025,976,906,843,800,756,749,696,649,620,560,539.

[0071]

[0072] Embodiment 4:

[0073] 1 H NMR(CDCl3,400MHz): δ7.16-6.78(br,3H,C6 H 5),6.78-6.18(br,2H,C6 H 5),4.57-3.94(br,2H,OC H2CF3),2.11-1.59(br,1H C H CH2), 1.59-1.23(br, 2H CHC H 2).

[0074] 31 P NMR (CDCl3, 162MHZ): δ19.91, 19.61, 16.94.

[0075] IR(neat,ATR,cm -1 ):3103,3083,3060,3026,3001,2923,2851,1601,1583,1493,1452,1419,1373,1287,1260,1170,1132,1070,1027,1003,962,906,874,841,755,748,695,660,537.

[0076]

[0077] Embodiment 5:

[0078] 1 H NMR (CDCl3, 400MHz): δ7.25-6.76(br), 6.75-6.00(br), 2.04-1.61(br, 1HC H CH2), 1.58-1.16(br,2H CHC H 2).

[0079] 31 P NMR (CDCl3, 162MHZ): δ10.54.

[0080] IR(neat,ATR,cm -1 ):3102,3083,3060,3025,3000,2922,2851,1943,1869,1801,1749,1601,1584,1540,1492,1451,1375,1262,1213,1190,1154,1070,1027,980,964,933,927,906,841,802,753,748,695,619,539.

[0081]

[0082] Embodiment 6:

[0083] 1H NMR(CDCl3,400MHz)δ7.17-6.73(br),6.73-6.00(br),2.04-1.61(br,1HC H CH2),1.60-1.12(br,2H CHC H 2).

[0084] 31 P NMR(CDCl3,162MHZ):δ9.97.

[0085] IR(neat,ATR,cm -1 )3104,3083,3060,3062,3002,2921,2849,1601,1492,1452,1373,1277,1262,1180,1133,1106,1027,928,905,843,801,755,696,636,617,537。

Claims

1. A manganese-catalyzed aromatic C(sp 2 A method for modifying polystyrene after polymerization by phosphorylation of )-H bonds, characterized in that: The method comprises the following steps: adding polystyrene, phosphate ester and manganese catalyst into an organic solvent for heating reaction, and after the reaction, performing post-treatment to obtain a phosphorylated polystyrene polymer; The reaction formula is as follows: Wherein, R is a C1-C4 alkyl group, a trifluoroethyl group, a substituted or unsubstituted phenyl group, and the substituent on the phenyl group is a C1-C4 alkyl group or a C1-C4 alkoxy group; y = 1-x, y represents the grafting rate; The range of y is 5% to 20%.

2. The manganese-catalyzed aromatic C (sp 2 A method for modifying polystyrene after polymerization by phosphorylation of a )-H bond, characterized in that R is one of methyl, ethyl, butyl, 2,2,2-trifluoroethyl or phenyl.

3. The manganese-catalyzed aromatic C (sp 2 A method for modifying polystyrene after polymerization by phosphorylation of )-H bonds, characterized in that the polystyrene is any one of commercial polystyrene and waste foam polystyrene; The M of polystyrene n =140.0~160.0kg·mol -1 , 4. The manganese-catalyzed aromatic C(sp 2 A method for modifying polystyrene after polymerization by phosphorylation of )-H bonds, characterized in that the manganese catalyst is anhydrous manganese acetate.

5. The manganese-catalyzed aromatic C (sp 2 A method for modifying polystyrene after polymerization by phosphorylation of )-H bonds, characterized in that: The phosphate ester is any one of dimethyl phosphite, diethyl phosphite, dibutyl phosphite, bis(2,2,2-trifluoroethyl)phosphite and diphenyl phosphite.

6. The manganese-catalyzed aromatic C(sp 2 A method for modifying polystyrene after polymerization by phosphorylation of )-H bonds, characterized in that: The organic solvent is any one of tetrahydrofuran, toluene, dichloroethane, acetic acid, and N,N-dimethylformamide (DMF).

7. The manganese-catalyzed aromatic C (sp 2 A method for modifying polystyrene after polymerization by phosphorylation of )-H bonds, characterized in that: The reaction temperature is 70-90°C and the reaction time is 8-15h.

8. The manganese-catalyzed aromatic C(sp 2 A method for modifying polystyrene after polymerization by phosphorylation of )-H bonds, characterized in that: In terms of molar amount, the ratio of polystyrene: phosphate ester: manganese catalyst is 1:1-1.1:0.2-0.

5.

9. The manganese-catalyzed aromatic C (sp 2 A method for modifying polystyrene after polymerization by phosphorylation of )-H bonds, characterized in that: The post-treatment steps are: dissolve and elute the reaction solution with dichloromethane and transfer it to a pear-shaped separatory funnel. The organic phase is washed with water three to five times, dried with anhydrous sodium sulfate, concentrated, and the mixed solution is poured into methanol to precipitate the product, and then filtered to obtain a solid precipitate, which is then dried in vacuo.

10. The manganese-catalyzed aromatic C (sp 2 A method for modifying polystyrene after polymerization by phosphorylation of )-H bonds, characterized in that: The phosphorylated polystyrene polymer structure is one of the compounds shown in formula (I-1) to formula (I-5):

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